WASHINGTON — Early in the second quarter, when the Knicks trailed the winless Wizards by 16 points, coach Mike D’Antoni sat on the hottest seat in Washington, D.C., outside President Obama.

But the “Broadway Bigs’’ — and sensational rookie Iman Shumpert — lived up to their hype to key a wonderful comeback last night, powering the Knicks to a desperately needed 99-96 victory over the 0-7 Wizards at Verizon Center.

Without any help from their starting backcourt, the Knicks’ frontcourt dynamos of Carmelo Anthony, Amar’e Stoudemire and Tyson Chandler combined for 72 points and 34 rebounds, with Shumpert starting the second half and doing almost everything right in just his third career game.

Anthony, playing with groin pain that was later diagnosed as a sore lower back, finished with 37 points including the game-winning 3-pointer from the right wing with 15.9 seconds left. The rousing victory before a few thousand transplanted Knicks fans temporarily eased the panic of two straight home losses to Eastern dregs Toronto and Charlotte that had Knick fans calling for D’Antoni’s head.

Anthony, who was slightly limping in the final two minutes, said he expects to play tonight in Detroit.

“It was a great comeback win,’’ Anthony said. “We needed this one. For us to give up 32 points [in the first quarter] is unacceptable.”

Because of his lame-duck status, D’Antoni might not be able to survive a dreadful start, and he seemed to know it.

“We did not hang our heads but obviously we were feeling a little bit of the pressure [early],’’ said D’Antoni, whose club fell behind 34-18 early in the second. “We did some good things but we have a lot of work to do.’’

The Knicks’ starting backcourt was again pitiful, combining for two points. Starting point guard Toney Douglas was benched as he went scoreless with zero assists in 11:35. He was 0 for 5 from the field. Starting shooting guard Landry Fields, who is playing with a sprained thumb, notched two points.

D’Antoni finally made the move to Shumpert to start the second half and could go that way tonight. Shumpert’s energy on both ends and playmaking was infectious as he scored 10 points with seven assists and five steals with his college coach, former Georgia Tech coach Paul Hewitt, in attendance.

“I still want to think about it,’’ said D’Antoni, who backed off starting Shumpert last night. “We don’t want to lose Toney, but we’ll do what we have to do.’’

The Knicks (3-4) also got a giant lift from reserve point guard Mike Bibby, who had been invisible until last night. Bibby hit big shots in the fourth quarter and finished with 11 points, hitting all three of his 3-pointers on a night the club missed its first 10 treys.

Despite surging ahead by nine midway through the third, the Knicks let the Wizards back in it. When Wall threaded Bibby and Shumpert for a fastbreak layup, he gave the Wizards a 96-95 lead with 47 seconds left.

Then Anthony went to work. He broke free of Trevor Booker, with Anthony’s elbow accidently poking him in the eye. Stoudemire shoveled the ball to Anthony, who buried the trey, giving the Knicks the lead back for good at 98-96.

“They put a bigger guy on me in Booker,” Anthony said. “I felt I could get to my spots on the court and make shots. It was falling for me tonight.’’

Asked if he took more out of the big comeback or falling behind Washington by 16, D’Antoni said, “I’m an optimist. You want me to sleep tonight, right? As long as we stuck together, we’ll go with that one.’’